How far does it go!

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
Americannon
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Wed Sep 22, 2021 7:39 pm

I just wanted to see if anyone can suggest anything for more power. I have 4 2” valves coming into a 16 foot long exhaust pipe for a barrel. All are quick exhaust modified valves. A 2” ball valve is then opened to fire. A 1 pound project I made of spackle and a 4 inch Christmas globe had a hang time of 16 second at a 61° angle, 120 psi. Can someone help me with the math for velocity or flight travel? Thanks
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iknowmy3tables
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Wed Oct 06, 2021 9:45 am

Holy moly, looks like you're trying to blow up the moon friend, lol
Let me dust off my old that math part of my brain, I can't factor for wind resistance but I got 89.64m/s or 294.1fps as your estimated velocity work math attached

That's only based on the flight time and the initial angle and assuming a vacuum And a 9.8m/s^2 acceleration of gravity. To calculate based on the cannons specs like using the GGDT program I'd need the dimensions of your air chamber and maybe a better picture of the chamber and valves
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iknowmy3tables
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Wed Oct 06, 2021 10:09 am

My mistake I forgot your initial question of how far does it go,
Expanding the math a little bit ideally it flew 695meters or 2281feet
It's probably short of that distance a good bit because that doesn't factor drag resistance, is anyone here familiar with drag coefficients?
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Americannon
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Tue Oct 19, 2021 8:11 pm

What I have is a 26 gallon compressor body shooting at 100 psi is a 1 inch electric solenoid, 4- 2inch modified irrigation valves with 1 inch tubing to a manifold and for 2 inch exhaust pipe going from each valve to the barrel that a 16 foot long and 4 inch diameter. The projectile is 1.4 pounds and had a flight type of 16 seconds at a 45° angle Can anybody suggest a better round for the further flight I have PVC I turned down on a lath With an aluminum Dow was for fins welded.
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Americannon
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Tue Oct 19, 2021 8:18 pm

Here’s the round I can’t post video. If anybody can suggest A faster round let me know I’ll make it. And just to be clear I’m not shooting missiles they identify as model rockets!
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jimmy101
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Fri Oct 22, 2021 7:43 pm

With four valve in parallel, I wonder if the opening of one inhibits the opening of the others? Do all four valves actually open together or do they inhibit each other?
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Americannon
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Fri Oct 22, 2021 11:55 pm

All open at once same size hoses,
iknowmy3tables
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Sat Oct 23, 2021 11:02 pm

good news while it was fun to refresh my trigonometry and kinematic equations I found a projectile calculator online
as soon as you enter an initial height time in flight and angle you should get a result https://www.omnicalculator.com/physics/ ... ile-motion
based on your 16seconds at 45 degrees I got an estimate 364fps speed and a distance of 4118feet

so I ran some of the dimensions you gave through GGDT I approximated some numbers line the internal dimensions and weight of diaphragm on the sprinkler valves the program really lowballs your estimate velocity at around 279fps and tweaking numbers around didn't really help,

going back to projectile flight calculation I'm inclined to believe it's closer to the higher numbers if you tweak the projectile motion calculator it says you'd have to have a flight time closer to 12 seconds for the velocity to be that low
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